package Hash;
import AVLTree.AVLTree;
import java.util.TreeMap;
import BinarySearchTree.BST;

public class HashTable<K, V>  {

    private final int[] capacity = {53, 97, 193, 389, 769, 1543, 3079, 6151, 12289, 24593,
                                 49157, 98317, 196613, 393241, 786433, 1572869, 3145739, 6291469,
                                 12582917, 25165843, 50331653, 100663319, 201326611, 402653189, 805306457, 1610612741};

    private static final int upperTol = 10;
    private static final int lowerTol = 2;
    //扩容 以及 缩容
    private int capacityIndex = 0;
    // capacity 数组的索引

    private TreeMap<K, V>[] hashtable;
    //K 要求 实现 Comparable 的
    private int M;
    private int size;

    public HashTable(){
        this.M = capacity[capacityIndex];
        size = 0;
        hashtable = new TreeMap[M];
        for(int i = 0; i < M ; i++)
            hashtable[i] = new TreeMap<>();
    }

    private int hash(K key){
        return key.hashCode() & 0x7fffffff % M;
        // 消除其 所 对应的符号
    }

    public int getSize(){
        return size;
    }

    public void add(K key, V value){
        TreeMap<K, V> map = hashtable[hash(key)];
        if(map.containsKey(key))
            map.put(key, value);  //修改内容 value
        else{
            map.put(key, value);
            size ++;

            if(size >= upperTol * M && capacityIndex + 1 < capacity.length) {
                capacityIndex ++;
                resize(capacity[capacityIndex]);
            }
        }
    }

    public V remove(K key){
        TreeMap<K, V> map = hashtable[hash(key)];
        V ret = null;
        if(map.containsKey(key)){
            ret = map.remove(key);
            size--;

            if(size < lowerTol * M && capacityIndex - 1 >= 0){
                capacityIndex --;
                resize(capacity[capacityIndex]);
            }
        }
        return ret;
    }

    public void set(K key, V value){
        TreeMap<K, V> map = hashtable[hash(key)];
        if(!map.containsKey(key))
            throw new IllegalArgumentException(key + " does's exixt!");

        map.put(key, value);
    }

    public boolean contains(K key){
        return hashtable[hash(key)].containsKey(key);
    }

    public V get(K key){
        return hashtable[hash(key)].get(key);
    }

    private void resize(int newM){
        TreeMap<K, V>[] newHashTable = new TreeMap[newM];
        for(int i = 0; i < newM; i++)
            newHashTable[i] = new TreeMap<>();

        int oldM = M;
        this.M = newM;   //更新 M 的值
        for(int i = 0; i < oldM; i++){
            TreeMap<K, V> map = hashtable[i];
            for(K key: map.keySet())
                newHashTable[hash(key)].put(key, map.get(key));
        }

        this.hashtable = newHashTable;
    }
}
